boards: arm: stm32h573 disco kit enables the CAN bus

Enable the canbus instance can1 on the stm32h573i_dk board
with arbitrary pins selection for fdcan rx & tx.
Select the PLL1_Q as FDCAN clock source (common to can 1 & 2).
Used for tests/drivers/can/api/ validation only.

Signed-off-by: Francois Ramu <francois.ramu@st.com>